Myelin produced by oligodendrocytes is essential for brain development and function. Dysfunction of oligodendrocytes and myelin is now thought to contribute to many neurological deficits associated with multiple sclerosis, schizophrenia, depression and Alzheimer's disease. However, the signals between myelinating oligodendrocytes and their underlying axons that control the myelination process remain largely unknown. This is in part due to lack of efficient in vitro myelination models that recapture key events of myelinating axons by oligodendrocytes in the central nervous system (CNS). The long-term goal of our research is to develop and utilize microsystems toward understanding the molecular and cellular basis of CNS myelination/demyelination and to develop strategies that promote myelin repair after injury. The purpose of this proposal is to develop and implement a novel in vitro CNS myelination system that enables precise control over various signaling factors in myelinogenesis aimed at uncovering the molecular basis of myelination and promoting myelin repair. Through an innovative and multidisciplinary approach, we have recently developed a novel compartmentalized myelination co-culture microsystem where axons from cortical neurons are guided to grow away from cell bodies into a fluidically isolated microenvironment where they interact with and are ensheathed by oligodendrocytes. In this proposal, we will further develop our preliminary microdevice into a novel in vitro CNS myelination microsystem that can accurately control the positions and densities of multiple cell types with single cell resolution, can apply localized chemical stimuli with precise spatial and temporal resolution, and can apply localized electrical stimuli, all at high throughput. We will first characterize myelinogenesis in the myelination microsystem. We will visualize the myelination process and examine specifically the role of cell to cell interactions, growth and inhibition factors, electrical stimulation mimicking neuronal activity in regulating the development of myelinating oligodendrocytes. Axonal neuregulin-1 determines the onset and the extent of myelination in the peripheral nervous system, but its role in CNS myelination is not clear. Therefore, we will specifically determine the role of neuregulin-1 and members of ciliary neurotrophic factor family in regulating the development of myelinating- oligodendrocytes. Finally, the integrated multielectrode arrays will be used to selectively stimulate neurons and study the effect of axonal firing on myelinogenesis. These studies should provide important new insights into the mechanisms responsible for CNS axon myelination as well as a powerful CNS myelination model system that can be exploited for myelin researches and drug development and testing. PUBLIC HEALTH RELEVANCE: Upon completion of this proposal, we hope to establish a novel model for studying myelination, a process essential to brain functions, and to uncover signals that promote myelination and thus facilitate myelin repair in demyelinating diseases. The unique feature of our cell culture microsystem also allows it to be used for screening and testing drugs for neurological diseases associated with myelin dysfunction such as multiple sclerosis, Alzheimer's disease and schizophrenia.